Möbius transformation of the complex plane

154 Views Asked by At

Let $\phi_{\alpha}(z)=\frac{z-\alpha}{1-\bar{\alpha}z}$ for $0<|\alpha|<1$

Find all the line $L$ in the complex plane such that $\phi_{\alpha} (L)=L$

Can you help me?

1

There are 1 best solutions below

3
On BEST ANSWER

Hint: Möbius transformations take lines and circles to lines and circles. The lines are distinguished from circles in that they go through $\infty$ (in the extended complex plane, i.e. the Riemann sphere). What does this transformation do to $\infty$, and what does it map to $\infty$?